Ruthenium-Catalyzed Synthesis of Cyclic Imides

Significance

Reported here is the direct synthesis of cyclic imides from diols and primary amines using an in situ generated ruthenium hydride based catalyst and an N-heterocyclic carbene precursor, 1,3-diisopropylimidazolium bromide, as ligand. The reaction is compatible with alkyl- and benzylamines and various diols. Based on experimental observations and on previous suggested mechanisms for amide formation (S. H. Hong and co-workers J. Org. Chem. 2010, 75, 3002; C. Gunanathan, Y. Ben-David, D. Milstein Science 2007, 317, 790), the authors suggested that the imide product is formed via an amide intermediate followed by intramolecular cyclization.